Contact lenses have been used commercially to improve vision since at least the 1950s. The first contact lenses were made of hard materials and as such were somewhat uncomfortable to users. Modern soft contact lenses are made of softer materials, typically hydrogels. Recently soft contact lenses made from silicone hydrogels have been introduced. Silicone hydrogel are water-swollen polymer networks that have high oxygen permeability. These lenses provide a good level of comfort to many lens wearers, but there are some users who experience discomfort and excessive ocular deposits leading to reduced visual acuity when using these lenses. This discomfort and deposits has been attributed to the hydrophobic character of the surfaces of lenses and the interaction of those surfaces with the protein, lipids and mucin and the hydrophilic surface of the eye.
Others have tried to alleviate this problem by coating the surface of silicone hydrogel contact lenses with hydrophilic coatings, such as plasma coatings
Cyclic polyamides, such as polyvinylpyrollidone have been incorporated into both conventional and silicone containing hydrogel formulations and contact lenses. Poly(meth)acrylamide and N-substituted poly(meth)acrylamides have been disclosed to be hydrophilic IPN agents which may be incorporated into conventional (non-silicone containing) hydrogels.
Modifying the surface of a polymeric article by adding polymerizable surfactants to a monomer mix used to form the article has also been disclosed. However, lasting in vivo improvements in wettability and reductions in surface deposits are not likely.
Polyvinylpyrrolidone (PVP) or poly-2-ethyl-2-oxazoline have been added to a hydrogel forming composition to form an interpenetrating network which shows a low degree of surface friction, a low dehydration rate and a high degree of biodeposit resistance. However, the hydrogel formulations disclosed are conventional hydrogels and there is no disclosure on how to incorporate hydrophobic components, such as siloxane monomers, without causing insolubility of the hydrogel-forming composition.
While it may be possible to incorporate high molecular weight polymers as internal wetting agents into silicone hydrogel lenses, such polymers can be difficult to solubilize in reaction mixtures which contain silicones.
Therefore it would be advantageous to find additional high molecular weight hydrophilic polymers which may be incorporated into a lens formulation to improve wettability of the lens without a surface treatment.